diff options
Diffstat (limited to 'vendor/gopkg.in/square/go-jose.v2/jwk.go')
-rw-r--r-- | vendor/gopkg.in/square/go-jose.v2/jwk.go | 760 |
1 files changed, 760 insertions, 0 deletions
diff --git a/vendor/gopkg.in/square/go-jose.v2/jwk.go b/vendor/gopkg.in/square/go-jose.v2/jwk.go new file mode 100644 index 000000000..2dc6aec4b --- /dev/null +++ b/vendor/gopkg.in/square/go-jose.v2/jwk.go @@ -0,0 +1,760 @@ +/*- + * Copyright 2014 Square Inc. + * + * Licensed under the Apache License, Version 2.0 (the "License"); + * you may not use this file except in compliance with the License. + * You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ + +package jose + +import ( + "bytes" + "crypto" + "crypto/ecdsa" + "crypto/elliptic" + "crypto/rsa" + "crypto/sha1" + "crypto/sha256" + "crypto/x509" + "encoding/base64" + "encoding/hex" + "errors" + "fmt" + "math/big" + "net/url" + "reflect" + "strings" + + "golang.org/x/crypto/ed25519" + + "gopkg.in/square/go-jose.v2/json" +) + +// rawJSONWebKey represents a public or private key in JWK format, used for parsing/serializing. +type rawJSONWebKey struct { + Use string `json:"use,omitempty"` + Kty string `json:"kty,omitempty"` + Kid string `json:"kid,omitempty"` + Crv string `json:"crv,omitempty"` + Alg string `json:"alg,omitempty"` + K *byteBuffer `json:"k,omitempty"` + X *byteBuffer `json:"x,omitempty"` + Y *byteBuffer `json:"y,omitempty"` + N *byteBuffer `json:"n,omitempty"` + E *byteBuffer `json:"e,omitempty"` + // -- Following fields are only used for private keys -- + // RSA uses D, P and Q, while ECDSA uses only D. Fields Dp, Dq, and Qi are + // completely optional. Therefore for RSA/ECDSA, D != nil is a contract that + // we have a private key whereas D == nil means we have only a public key. + D *byteBuffer `json:"d,omitempty"` + P *byteBuffer `json:"p,omitempty"` + Q *byteBuffer `json:"q,omitempty"` + Dp *byteBuffer `json:"dp,omitempty"` + Dq *byteBuffer `json:"dq,omitempty"` + Qi *byteBuffer `json:"qi,omitempty"` + // Certificates + X5c []string `json:"x5c,omitempty"` + X5u *url.URL `json:"x5u,omitempty"` + X5tSHA1 string `json:"x5t,omitempty"` + X5tSHA256 string `json:"x5t#S256,omitempty"` +} + +// JSONWebKey represents a public or private key in JWK format. +type JSONWebKey struct { + // Cryptographic key, can be a symmetric or asymmetric key. + Key interface{} + // Key identifier, parsed from `kid` header. + KeyID string + // Key algorithm, parsed from `alg` header. + Algorithm string + // Key use, parsed from `use` header. + Use string + + // X.509 certificate chain, parsed from `x5c` header. + Certificates []*x509.Certificate + // X.509 certificate URL, parsed from `x5u` header. + CertificatesURL *url.URL + // X.509 certificate thumbprint (SHA-1), parsed from `x5t` header. + CertificateThumbprintSHA1 []byte + // X.509 certificate thumbprint (SHA-256), parsed from `x5t#S256` header. + CertificateThumbprintSHA256 []byte +} + +// MarshalJSON serializes the given key to its JSON representation. +func (k JSONWebKey) MarshalJSON() ([]byte, error) { + var raw *rawJSONWebKey + var err error + + switch key := k.Key.(type) { + case ed25519.PublicKey: + raw = fromEdPublicKey(key) + case *ecdsa.PublicKey: + raw, err = fromEcPublicKey(key) + case *rsa.PublicKey: + raw = fromRsaPublicKey(key) + case ed25519.PrivateKey: + raw, err = fromEdPrivateKey(key) + case *ecdsa.PrivateKey: + raw, err = fromEcPrivateKey(key) + case *rsa.PrivateKey: + raw, err = fromRsaPrivateKey(key) + case []byte: + raw, err = fromSymmetricKey(key) + default: + return nil, fmt.Errorf("square/go-jose: unknown key type '%s'", reflect.TypeOf(key)) + } + + if err != nil { + return nil, err + } + + raw.Kid = k.KeyID + raw.Alg = k.Algorithm + raw.Use = k.Use + + for _, cert := range k.Certificates { + raw.X5c = append(raw.X5c, base64.StdEncoding.EncodeToString(cert.Raw)) + } + + x5tSHA1Len := len(k.CertificateThumbprintSHA1) + x5tSHA256Len := len(k.CertificateThumbprintSHA256) + if x5tSHA1Len > 0 { + if x5tSHA1Len != sha1.Size { + return nil, fmt.Errorf("square/go-jose: invalid SHA-1 thumbprint (must be %d bytes, not %d)", sha1.Size, x5tSHA1Len) + } + raw.X5tSHA1 = base64.RawURLEncoding.EncodeToString(k.CertificateThumbprintSHA1) + } + if x5tSHA256Len > 0 { + if x5tSHA256Len != sha256.Size { + return nil, fmt.Errorf("square/go-jose: invalid SHA-256 thumbprint (must be %d bytes, not %d)", sha256.Size, x5tSHA256Len) + } + raw.X5tSHA256 = base64.RawURLEncoding.EncodeToString(k.CertificateThumbprintSHA256) + } + + // If cert chain is attached (as opposed to being behind a URL), check the + // keys thumbprints to make sure they match what is expected. This is to + // ensure we don't accidentally produce a JWK with semantically inconsistent + // data in the headers. + if len(k.Certificates) > 0 { + expectedSHA1 := sha1.Sum(k.Certificates[0].Raw) + expectedSHA256 := sha256.Sum256(k.Certificates[0].Raw) + + if len(k.CertificateThumbprintSHA1) > 0 && !bytes.Equal(k.CertificateThumbprintSHA1, expectedSHA1[:]) { + return nil, errors.New("square/go-jose: invalid SHA-1 thumbprint, does not match cert chain") + } + if len(k.CertificateThumbprintSHA256) > 0 && !bytes.Equal(k.CertificateThumbprintSHA256, expectedSHA256[:]) { + return nil, errors.New("square/go-jose: invalid or SHA-256 thumbprint, does not match cert chain") + } + } + + raw.X5u = k.CertificatesURL + + return json.Marshal(raw) +} + +// UnmarshalJSON reads a key from its JSON representation. +func (k *JSONWebKey) UnmarshalJSON(data []byte) (err error) { + var raw rawJSONWebKey + err = json.Unmarshal(data, &raw) + if err != nil { + return err + } + + certs, err := parseCertificateChain(raw.X5c) + if err != nil { + return fmt.Errorf("square/go-jose: failed to unmarshal x5c field: %s", err) + } + + var key interface{} + var certPub interface{} + var keyPub interface{} + + if len(certs) > 0 { + // We need to check that leaf public key matches the key embedded in this + // JWK, as required by the standard (see RFC 7517, Section 4.7). Otherwise + // the JWK parsed could be semantically invalid. Technically, should also + // check key usage fields and other extensions on the cert here, but the + // standard doesn't exactly explain how they're supposed to map from the + // JWK representation to the X.509 extensions. + certPub = certs[0].PublicKey + } + + switch raw.Kty { + case "EC": + if raw.D != nil { + key, err = raw.ecPrivateKey() + if err == nil { + keyPub = key.(*ecdsa.PrivateKey).Public() + } + } else { + key, err = raw.ecPublicKey() + keyPub = key + } + case "RSA": + if raw.D != nil { + key, err = raw.rsaPrivateKey() + if err == nil { + keyPub = key.(*rsa.PrivateKey).Public() + } + } else { + key, err = raw.rsaPublicKey() + keyPub = key + } + case "oct": + if certPub != nil { + return errors.New("square/go-jose: invalid JWK, found 'oct' (symmetric) key with cert chain") + } + key, err = raw.symmetricKey() + case "OKP": + if raw.Crv == "Ed25519" && raw.X != nil { + if raw.D != nil { + key, err = raw.edPrivateKey() + if err == nil { + keyPub = key.(ed25519.PrivateKey).Public() + } + } else { + key, err = raw.edPublicKey() + keyPub = key + } + } else { + err = fmt.Errorf("square/go-jose: unknown curve %s'", raw.Crv) + } + default: + err = fmt.Errorf("square/go-jose: unknown json web key type '%s'", raw.Kty) + } + + if err != nil { + return + } + + if certPub != nil && keyPub != nil { + if !reflect.DeepEqual(certPub, keyPub) { + return errors.New("square/go-jose: invalid JWK, public keys in key and x5c fields to not match") + } + } + + *k = JSONWebKey{Key: key, KeyID: raw.Kid, Algorithm: raw.Alg, Use: raw.Use, Certificates: certs} + + k.CertificatesURL = raw.X5u + + // x5t parameters are base64url-encoded SHA thumbprints + // See RFC 7517, Section 4.8, https://tools.ietf.org/html/rfc7517#section-4.8 + x5tSHA1bytes, err := base64.RawURLEncoding.DecodeString(raw.X5tSHA1) + if err != nil { + return errors.New("square/go-jose: invalid JWK, x5t header has invalid encoding") + } + + // RFC 7517, Section 4.8 is ambiguous as to whether the digest output should be byte or hex, + // for this reason, after base64 decoding, if the size is sha1.Size it's likely that the value is a byte encoded + // checksum so we skip this. Otherwise if the checksum was hex encoded we expect a 40 byte sized array so we'll + // try to hex decode it. When Marshalling this value we'll always use a base64 encoded version of byte format checksum. + if len(x5tSHA1bytes) == 2*sha1.Size { + hx, err := hex.DecodeString(string(x5tSHA1bytes)) + if err != nil { + return fmt.Errorf("square/go-jose: invalid JWK, unable to hex decode x5t: %v", err) + + } + x5tSHA1bytes = hx + } + + k.CertificateThumbprintSHA1 = x5tSHA1bytes + + x5tSHA256bytes, err := base64.RawURLEncoding.DecodeString(raw.X5tSHA256) + if err != nil { + return errors.New("square/go-jose: invalid JWK, x5t#S256 header has invalid encoding") + } + + if len(x5tSHA256bytes) == 2*sha256.Size { + hx256, err := hex.DecodeString(string(x5tSHA256bytes)) + if err != nil { + return fmt.Errorf("square/go-jose: invalid JWK, unable to hex decode x5t#S256: %v", err) + } + x5tSHA256bytes = hx256 + } + + k.CertificateThumbprintSHA256 = x5tSHA256bytes + + x5tSHA1Len := len(k.CertificateThumbprintSHA1) + x5tSHA256Len := len(k.CertificateThumbprintSHA256) + if x5tSHA1Len > 0 && x5tSHA1Len != sha1.Size { + return errors.New("square/go-jose: invalid JWK, x5t header is of incorrect size") + } + if x5tSHA256Len > 0 && x5tSHA256Len != sha256.Size { + return errors.New("square/go-jose: invalid JWK, x5t#S256 header is of incorrect size") + } + + // If certificate chain *and* thumbprints are set, verify correctness. + if len(k.Certificates) > 0 { + leaf := k.Certificates[0] + sha1sum := sha1.Sum(leaf.Raw) + sha256sum := sha256.Sum256(leaf.Raw) + + if len(k.CertificateThumbprintSHA1) > 0 && !bytes.Equal(sha1sum[:], k.CertificateThumbprintSHA1) { + return errors.New("square/go-jose: invalid JWK, x5c thumbprint does not match x5t value") + } + + if len(k.CertificateThumbprintSHA256) > 0 && !bytes.Equal(sha256sum[:], k.CertificateThumbprintSHA256) { + return errors.New("square/go-jose: invalid JWK, x5c thumbprint does not match x5t#S256 value") + } + } + + return +} + +// JSONWebKeySet represents a JWK Set object. +type JSONWebKeySet struct { + Keys []JSONWebKey `json:"keys"` +} + +// Key convenience method returns keys by key ID. Specification states +// that a JWK Set "SHOULD" use distinct key IDs, but allows for some +// cases where they are not distinct. Hence method returns a slice +// of JSONWebKeys. +func (s *JSONWebKeySet) Key(kid string) []JSONWebKey { + var keys []JSONWebKey + for _, key := range s.Keys { + if key.KeyID == kid { + keys = append(keys, key) + } + } + + return keys +} + +const rsaThumbprintTemplate = `{"e":"%s","kty":"RSA","n":"%s"}` +const ecThumbprintTemplate = `{"crv":"%s","kty":"EC","x":"%s","y":"%s"}` +const edThumbprintTemplate = `{"crv":"%s","kty":"OKP",x":"%s"}` + +func ecThumbprintInput(curve elliptic.Curve, x, y *big.Int) (string, error) { + coordLength := curveSize(curve) + crv, err := curveName(curve) + if err != nil { + return "", err + } + + if len(x.Bytes()) > coordLength || len(y.Bytes()) > coordLength { + return "", errors.New("square/go-jose: invalid elliptic key (too large)") + } + + return fmt.Sprintf(ecThumbprintTemplate, crv, + newFixedSizeBuffer(x.Bytes(), coordLength).base64(), + newFixedSizeBuffer(y.Bytes(), coordLength).base64()), nil +} + +func rsaThumbprintInput(n *big.Int, e int) (string, error) { + return fmt.Sprintf(rsaThumbprintTemplate, + newBufferFromInt(uint64(e)).base64(), + newBuffer(n.Bytes()).base64()), nil +} + +func edThumbprintInput(ed ed25519.PublicKey) (string, error) { + crv := "Ed25519" + if len(ed) > 32 { + return "", errors.New("square/go-jose: invalid elliptic key (too large)") + } + return fmt.Sprintf(edThumbprintTemplate, crv, + newFixedSizeBuffer(ed, 32).base64()), nil +} + +// Thumbprint computes the JWK Thumbprint of a key using the +// indicated hash algorithm. +func (k *JSONWebKey) Thumbprint(hash crypto.Hash) ([]byte, error) { + var input string + var err error + switch key := k.Key.(type) { + case ed25519.PublicKey: + input, err = edThumbprintInput(key) + case *ecdsa.PublicKey: + input, err = ecThumbprintInput(key.Curve, key.X, key.Y) + case *ecdsa.PrivateKey: + input, err = ecThumbprintInput(key.Curve, key.X, key.Y) + case *rsa.PublicKey: + input, err = rsaThumbprintInput(key.N, key.E) + case *rsa.PrivateKey: + input, err = rsaThumbprintInput(key.N, key.E) + case ed25519.PrivateKey: + input, err = edThumbprintInput(ed25519.PublicKey(key[32:])) + default: + return nil, fmt.Errorf("square/go-jose: unknown key type '%s'", reflect.TypeOf(key)) + } + + if err != nil { + return nil, err + } + + h := hash.New() + h.Write([]byte(input)) + return h.Sum(nil), nil +} + +// IsPublic returns true if the JWK represents a public key (not symmetric, not private). +func (k *JSONWebKey) IsPublic() bool { + switch k.Key.(type) { + case *ecdsa.PublicKey, *rsa.PublicKey, ed25519.PublicKey: + return true + default: + return false + } +} + +// Public creates JSONWebKey with corresponding publik key if JWK represents asymmetric private key. +func (k *JSONWebKey) Public() JSONWebKey { + if k.IsPublic() { + return *k + } + ret := *k + switch key := k.Key.(type) { + case *ecdsa.PrivateKey: + ret.Key = key.Public() + case *rsa.PrivateKey: + ret.Key = key.Public() + case ed25519.PrivateKey: + ret.Key = key.Public() + default: + return JSONWebKey{} // returning invalid key + } + return ret +} + +// Valid checks that the key contains the expected parameters. +func (k *JSONWebKey) Valid() bool { + if k.Key == nil { + return false + } + switch key := k.Key.(type) { + case *ecdsa.PublicKey: + if key.Curve == nil || key.X == nil || key.Y == nil { + return false + } + case *ecdsa.PrivateKey: + if key.Curve == nil || key.X == nil || key.Y == nil || key.D == nil { + return false + } + case *rsa.PublicKey: + if key.N == nil || key.E == 0 { + return false + } + case *rsa.PrivateKey: + if key.N == nil || key.E == 0 || key.D == nil || len(key.Primes) < 2 { + return false + } + case ed25519.PublicKey: + if len(key) != 32 { + return false + } + case ed25519.PrivateKey: + if len(key) != 64 { + return false + } + default: + return false + } + return true +} + +func (key rawJSONWebKey) rsaPublicKey() (*rsa.PublicKey, error) { + if key.N == nil || key.E == nil { + return nil, fmt.Errorf("square/go-jose: invalid RSA key, missing n/e values") + } + + return &rsa.PublicKey{ + N: key.N.bigInt(), + E: key.E.toInt(), + }, nil +} + +func fromEdPublicKey(pub ed25519.PublicKey) *rawJSONWebKey { + return &rawJSONWebKey{ + Kty: "OKP", + Crv: "Ed25519", + X: newBuffer(pub), + } +} + +func fromRsaPublicKey(pub *rsa.PublicKey) *rawJSONWebKey { + return &rawJSONWebKey{ + Kty: "RSA", + N: newBuffer(pub.N.Bytes()), + E: newBufferFromInt(uint64(pub.E)), + } +} + +func (key rawJSONWebKey) ecPublicKey() (*ecdsa.PublicKey, error) { + var curve elliptic.Curve + switch key.Crv { + case "P-256": + curve = elliptic.P256() + case "P-384": + curve = elliptic.P384() + case "P-521": + curve = elliptic.P521() + default: + return nil, fmt.Errorf("square/go-jose: unsupported elliptic curve '%s'", key.Crv) + } + + if key.X == nil || key.Y == nil { + return nil, errors.New("square/go-jose: invalid EC key, missing x/y values") + } + + // The length of this octet string MUST be the full size of a coordinate for + // the curve specified in the "crv" parameter. + // https://tools.ietf.org/html/rfc7518#section-6.2.1.2 + if curveSize(curve) != len(key.X.data) { + return nil, fmt.Errorf("square/go-jose: invalid EC public key, wrong length for x") + } + + if curveSize(curve) != len(key.Y.data) { + return nil, fmt.Errorf("square/go-jose: invalid EC public key, wrong length for y") + } + + x := key.X.bigInt() + y := key.Y.bigInt() + + if !curve.IsOnCurve(x, y) { + return nil, errors.New("square/go-jose: invalid EC key, X/Y are not on declared curve") + } + + return &ecdsa.PublicKey{ + Curve: curve, + X: x, + Y: y, + }, nil +} + +func fromEcPublicKey(pub *ecdsa.PublicKey) (*rawJSONWebKey, error) { + if pub == nil || pub.X == nil || pub.Y == nil { + return nil, fmt.Errorf("square/go-jose: invalid EC key (nil, or X/Y missing)") + } + + name, err := curveName(pub.Curve) + if err != nil { + return nil, err + } + + size := curveSize(pub.Curve) + + xBytes := pub.X.Bytes() + yBytes := pub.Y.Bytes() + + if len(xBytes) > size || len(yBytes) > size { + return nil, fmt.Errorf("square/go-jose: invalid EC key (X/Y too large)") + } + + key := &rawJSONWebKey{ + Kty: "EC", + Crv: name, + X: newFixedSizeBuffer(xBytes, size), + Y: newFixedSizeBuffer(yBytes, size), + } + + return key, nil +} + +func (key rawJSONWebKey) edPrivateKey() (ed25519.PrivateKey, error) { + var missing []string + switch { + case key.D == nil: + missing = append(missing, "D") + case key.X == nil: + missing = append(missing, "X") + } + + if len(missing) > 0 { + return nil, fmt.Errorf("square/go-jose: invalid Ed25519 private key, missing %s value(s)", strings.Join(missing, ", ")) + } + + privateKey := make([]byte, ed25519.PrivateKeySize) + copy(privateKey[0:32], key.D.bytes()) + copy(privateKey[32:], key.X.bytes()) + rv := ed25519.PrivateKey(privateKey) + return rv, nil +} + +func (key rawJSONWebKey) edPublicKey() (ed25519.PublicKey, error) { + if key.X == nil { + return nil, fmt.Errorf("square/go-jose: invalid Ed key, missing x value") + } + publicKey := make([]byte, ed25519.PublicKeySize) + copy(publicKey[0:32], key.X.bytes()) + rv := ed25519.PublicKey(publicKey) + return rv, nil +} + +func (key rawJSONWebKey) rsaPrivateKey() (*rsa.PrivateKey, error) { + var missing []string + switch { + case key.N == nil: + missing = append(missing, "N") + case key.E == nil: + missing = append(missing, "E") + case key.D == nil: + missing = append(missing, "D") + case key.P == nil: + missing = append(missing, "P") + case key.Q == nil: + missing = append(missing, "Q") + } + + if len(missing) > 0 { + return nil, fmt.Errorf("square/go-jose: invalid RSA private key, missing %s value(s)", strings.Join(missing, ", ")) + } + + rv := &rsa.PrivateKey{ + PublicKey: rsa.PublicKey{ + N: key.N.bigInt(), + E: key.E.toInt(), + }, + D: key.D.bigInt(), + Primes: []*big.Int{ + key.P.bigInt(), + key.Q.bigInt(), + }, + } + + if key.Dp != nil { + rv.Precomputed.Dp = key.Dp.bigInt() + } + if key.Dq != nil { + rv.Precomputed.Dq = key.Dq.bigInt() + } + if key.Qi != nil { + rv.Precomputed.Qinv = key.Qi.bigInt() + } + + err := rv.Validate() + return rv, err +} + +func fromEdPrivateKey(ed ed25519.PrivateKey) (*rawJSONWebKey, error) { + raw := fromEdPublicKey(ed25519.PublicKey(ed[32:])) + + raw.D = newBuffer(ed[0:32]) + return raw, nil +} + +func fromRsaPrivateKey(rsa *rsa.PrivateKey) (*rawJSONWebKey, error) { + if len(rsa.Primes) != 2 { + return nil, ErrUnsupportedKeyType + } + + raw := fromRsaPublicKey(&rsa.PublicKey) + + raw.D = newBuffer(rsa.D.Bytes()) + raw.P = newBuffer(rsa.Primes[0].Bytes()) + raw.Q = newBuffer(rsa.Primes[1].Bytes()) + + if rsa.Precomputed.Dp != nil { + raw.Dp = newBuffer(rsa.Precomputed.Dp.Bytes()) + } + if rsa.Precomputed.Dq != nil { + raw.Dq = newBuffer(rsa.Precomputed.Dq.Bytes()) + } + if rsa.Precomputed.Qinv != nil { + raw.Qi = newBuffer(rsa.Precomputed.Qinv.Bytes()) + } + + return raw, nil +} + +func (key rawJSONWebKey) ecPrivateKey() (*ecdsa.PrivateKey, error) { + var curve elliptic.Curve + switch key.Crv { + case "P-256": + curve = elliptic.P256() + case "P-384": + curve = elliptic.P384() + case "P-521": + curve = elliptic.P521() + default: + return nil, fmt.Errorf("square/go-jose: unsupported elliptic curve '%s'", key.Crv) + } + + if key.X == nil || key.Y == nil || key.D == nil { + return nil, fmt.Errorf("square/go-jose: invalid EC private key, missing x/y/d values") + } + + // The length of this octet string MUST be the full size of a coordinate for + // the curve specified in the "crv" parameter. + // https://tools.ietf.org/html/rfc7518#section-6.2.1.2 + if curveSize(curve) != len(key.X.data) { + return nil, fmt.Errorf("square/go-jose: invalid EC private key, wrong length for x") + } + + if curveSize(curve) != len(key.Y.data) { + return nil, fmt.Errorf("square/go-jose: invalid EC private key, wrong length for y") + } + + // https://tools.ietf.org/html/rfc7518#section-6.2.2.1 + if dSize(curve) != len(key.D.data) { + return nil, fmt.Errorf("square/go-jose: invalid EC private key, wrong length for d") + } + + x := key.X.bigInt() + y := key.Y.bigInt() + + if !curve.IsOnCurve(x, y) { + return nil, errors.New("square/go-jose: invalid EC key, X/Y are not on declared curve") + } + + return &ecdsa.PrivateKey{ + PublicKey: ecdsa.PublicKey{ + Curve: curve, + X: x, + Y: y, + }, + D: key.D.bigInt(), + }, nil +} + +func fromEcPrivateKey(ec *ecdsa.PrivateKey) (*rawJSONWebKey, error) { + raw, err := fromEcPublicKey(&ec.PublicKey) + if err != nil { + return nil, err + } + + if ec.D == nil { + return nil, fmt.Errorf("square/go-jose: invalid EC private key") + } + + raw.D = newFixedSizeBuffer(ec.D.Bytes(), dSize(ec.PublicKey.Curve)) + + return raw, nil +} + +// dSize returns the size in octets for the "d" member of an elliptic curve +// private key. +// The length of this octet string MUST be ceiling(log-base-2(n)/8) +// octets (where n is the order of the curve). +// https://tools.ietf.org/html/rfc7518#section-6.2.2.1 +func dSize(curve elliptic.Curve) int { + order := curve.Params().P + bitLen := order.BitLen() + size := bitLen / 8 + if bitLen%8 != 0 { + size = size + 1 + } + return size +} + +func fromSymmetricKey(key []byte) (*rawJSONWebKey, error) { + return &rawJSONWebKey{ + Kty: "oct", + K: newBuffer(key), + }, nil +} + +func (key rawJSONWebKey) symmetricKey() ([]byte, error) { + if key.K == nil { + return nil, fmt.Errorf("square/go-jose: invalid OCT (symmetric) key, missing k value") + } + return key.K.bytes(), nil +} |